Beam delivery with fibers

Dinesh · Post by **Dinesh** » Thu Jun 12, 2014 8:40 am

Yes, this has been done a number of times over the years. I'm not sure where and when the paper Ed references is published , since there is no journal or conference reference (although the latest reference in the paper is ref 23, which puts the date as being after 1986), but here are papers ranging from 1988 to 2011
http://www.opticsinfobase.org/ao/abstra ... 27-17-3723
http://www.opticsinfobase.org/oe/abstra ... e-19-1-247

The thing I notice is that all of these papers refer to the technique as being a technique for interferometry, which leads one to the conclusion that the aperture must have been small. This is not unusual, since the NA of these fibers is pretty small. So, is the holographic recording of a large diffuse object beam possible? I suppose we await John's experiments for that.

Ed Wesly · Post by **Ed Wesly** » Thu Jun 12, 2014 12:07 pm

Proceedings of the SPIE Vol. 746, 1987.

Dinesh · Post by **Dinesh** » Thu Jun 12, 2014 1:33 pm

Ed Wesly wrote:Proceedings of the SPIE Vol. 746, 1987.

Got it http://proceedings.spiedigitallibrary.o ... id=1246824. Now that Ed has put up the paper, we don't have to pay SPIE $18 for it.

Ed Wesly · Post by **Ed Wesly** » Fri Jun 13, 2014 7:03 am

All my papers are available for your viewing pleasure at: http://edweslystudio.com/Publications/Publications.html

Ed Wesly · Post by **Ed Wesly** » Fri Jun 20, 2014 7:13 am

Here is a beams splitting, fiber launching unit in my possession.

One of maybe a dozen made. Graham Saxby mentions it in one of his editions.

Can be yours, serious offers only, PM me c/o this forum.

Holomark · Post by **Holomark** » Fri Jun 27, 2014 5:36 pm

Ed,
That beam splitting, fiber launching unitlooks nice.
It looks like the DBL-3 splits the beam twice to make three beams (1 reference and 2 object). I wonder what kind of lense is at the end and how large an object can be illuminated? Is there any adjustment or way to change the output (divergence)? Will this work with red and Green?
Mark

Ed Wesly · Post by **Ed Wesly** » Sat Jun 28, 2014 7:39 am

I wonder what kind of lense is at the end?

There is a GRIN (Gradient Refractive INdex) rod lens to launch the beam into the fiber. The output has no lens, the spread of the beam determined by the Numerical Aperture of the fiber.

and how large an object can be illuminated?

The picture on the brochure pretty accurately depicts a set up to make a 65 mm square (2 1/2") plate. Moving everything further back will allow you to make larger holograms of larger objects.

Is there any adjustment or way to change the output (divergence)?

Not built in to the system. Lenses after the fiber output can control the divergence, but they have to be pretty clean, as the light emerging from the fiber is as clean as spatially filtered light. Negative lenses will increase divergence, positive ones will decrease divergence or even collimate or focus the beams depending on where they are placed.

Will this work with red and Green?

Good question. 315Ms had not yet been invented, so we never tried one of those in the device. Nor argons, either, even though we had them, as most air to glass interfaces were AR-coated for He-Ne, plus the way the beamsplitters worked (yes, 2 of them, to generate the 3 beams) tilted a prism to vary the ratio, which had a He-Ne wavelength specific coating, as Bill Durell, the father of the device said, "changes the Brewster angle to 45 degrees" instead of the typical 57 or so of uncoated glass. So it might be interesting to see what does come out! But I have a feeling that one color would be less divergent than the other, even though they are both coming out of the same fiber.

A very interesting device, I only know of two other customers for this thing, so who knows how many were really made. Obviously it didn't revolutionize holographing as promised!

John Klayer · Post by **John Klayer** » Sat Jun 28, 2014 7:26 pm

Here's a fiber beam splitter I threw together. It is three Toslink splitter taped together and linked with short fibers. The first splits 1/2 to the object, 1/2 to the next and so on till the third splits one of its /2 to the reference, the remainder to the object. There is a lot of loss. I still haven't got around to shooting a hologram with it yet.

Jem · Post by **Jem** » Sat Jul 05, 2014 11:43 am

I tracked Bill Durell down a year or so ago, had a long telephone conversation with him from the UK. An incredibly interesting man who couldn't believe that someone would take the time and trouble to look him up and want to speak to him about something that he invented years ago.

I spent countless hours launching beams into fibers for holography purposes. Eventually decided that it was easier to lock everything down solid so gave up on the fibers idea for a while. I may revisit it someday...

Ed, I would be interested to learn how much you'd be looking at for that unit.

John Klayer · Post by **John Klayer** » Sun Jul 06, 2014 2:56 am

Perhaps I should show a hologram made with a multi mode fiber for the reference, "Little Guy"
http://www.bing.com/videos/search?q=hol ... 360F820CD0